Volute Structure, Centrifugal Compressor and Refrigeration Equipment

ABSTRACT

The present application discloses a volute structure, a centrifugal compressor and a refrigeration device. The volute structure comprises: a cabinet ( 8 ), a volute casing ( 1 ) and a backflow device ( 5 ); the volute casing ( 1 ) comprises an inner volute and an outer volute separately provided, a fluid flow passage being formed between the inner volute and outer volute, and the inner volute and backflow device ( 5 ) being disposed together. The present application increases the length of the first-stage diffuser, improving the diffusion effect of air entering the first-stage diffuser and thus enhancing the unit performance of the centrifugal compressor.

The present application claims the priority of a Chinse patentapplication No. 201410549697.8 entitled “Volute Structure, CentrifugalCompressor, and Refrigeration Equipment” filed on Oct. 16, 2014, allcontents of which are incorporated in the present application byreference.

FIELD OF THE INVENTION

The present application relates to refrigerant equipment, and morespecifically relates to a volute structure, a centrifugal compressor anda refrigerant equipment.

BACKGROUND OF THE INVENTION

In double-stage and multi-stage centrifugal compressor structures, inorder to reduce the length of a cantilever end of a main shaft, enhancea threshold rotating speed, and enhance stability, a pneumatic part ofmulti-stage compression is always made very compact. However, thepneumatic part of a centrifugal compressor includes many components,such that it is very difficult to arrange the components of thepneumatic part of the centrifugal compressor. Particularly in a volutefront tilting-type multi-stage compression, the volute is very close toa curve passage behind a first-stage diffuser outlet, such that thestructure is not satisfied.

FIG. 1 is a schematic diagram of a layout of a pneumatic part of avolute front tilting-type double-stage centrifugal compressor, in whichan internal arc cavity of the volute faces downstream of air flow. Thecentrifugal type compressor pneumatic part mainly comprises a deflector,a first-stage impeller, a first-stage diffuser, a curve passage, abackflow device, a second-stage impeller, a second-stage diffuser, and avolute 21. The centrifugal compressor comprises a main shaft 20 and thevolute 21. In the prior art, in order to improve the structure, thecurve passage is arranged as far as possible from the volute 21 bynarrowing the length of the first-stage diffuser, while increasing thecantilever end length of the main shaft 20.

The inventors find that the prior art at least has the followingdrawbacks: narrowing the length of the first-stage diffuser section willresult in that the gas entering the centrifugal compressor cannot besufficiently diffused, which will deteriorate the performance of thecentrifugal compressor. Further, increasing the length of the main shaft20 results in reduction of the threshold rotating speed, deteriorationof the operation stability, and degradation of performance of thecompressor.

SUMMARY OF THE INVENTION

One of objectives of the present application is to provide a volutestructure, a centrifugal compressor, and a refrigerant device, foroptimizing a pneumatic structure of the existing centrifugal compressor,and enhancing unit performance and stability of the compressor.

In order to achieve the objective above, the present applicationprovides the following technical solutions:

The present application provides a volute structure, comprising: acabinet, a volute housing, and a backflow device; the volute housingcomprising an inner volute and an outer volute which are separatelyprovided, a fluid passage being formed between the inner volute and theouter volute; and the inner volute being arranged with the backflowdevice.

In the above volute structure, optionally, the inner volute and thebackflow device are casted integrally.

In the above volute structure, optionally, outer volute and the cabinetare casted integrally.

In the above volute structure, optionally, a connection portion betweenthe inner volute and the outer volute is rounded.

In the above volute structure, optionally, the volute structure furthercomprises a curve passage that is fixed on backflow device.

In the above volute structure, optionally, the curve passage and thebackflow device are casted integrally.

The present application further provides a centrifugal compressor,comprising a volute structure according to the present application

In the above centrifugal compressor, optionally, the centrifugalcompressor also comprises a housing, and the volute structure furthercomprises a one-stage diffuser; and the housing, the cabinet, theone-stage diffuser, and the backflow device enclose a one-stage gassupply cavity.

In the above centrifugal compressor, optionally, the centrifugalcompressor is a double-stage or multi-stage centrifugal compressor.

The present application further provides a refrigerant device,comprising a centrifugal compressor according to the presentapplication.

Based on the technical solution above, embodiments of the presentapplication could at least achieve the following technical effect:

In the technical solutions above, the volute housing is divided into twoseparate parts: an inner volute and an outer volute. Moreover, the innervolute and the backflow device are arranged together, which saves thespace occupied by the inner volute and the backflow device, downsizesthe structure of connecting the volute, backflow device, and curvelinkage, such that the volute housing and the curve are arranged closeenough in the structure. Meanwhile, it guarantees enough length of thefirst-stage diffuser and improves the diffusion effect of the gasentering into the first-stage diffuser, thereby enhancing unitperformance and the operation stability of the centrifugal compressor.In addition, the technical solution also shortens the length of a mainshaft, thereby raising the threshold rotating speed of the rotary partof the compressor, enhancing the operation stability and compressorperformance of the centrifugal compressor.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The drawings illustrated here are for providing further understanding ofthe present application and thus constitute part of the presentapplication. The exemplary embodiments of the present application anddepictions thereof are for interpreting the present application, notconstituting improper limitations of the present application. In thedrawings:

FIG. 1 is a layout diagram of a pneumatic part of a volute front tiltingtype double-stage centrifugal compressor in the prior art;

FIG. 2 is a partial section view of a volute structure applied to acentrifugal compressor according to embodiments of the presentapplication;

REFERENCE NUMERALS

1. Casing; 2. First-stage impeller; 3. First-stage diffuser; 4. CurvePassage; 5. Backflow device; 6. Second-stage impeller; 7. Volutehousing; 8. Cabinet; 9. First-stage air supply cavity; 10. Second-stagediffuser; 20. Main shaft; 21. Volute.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the technical solution of the present application will bedescribed in more detail with reference to FIG. 2. Any technicalsolution resulting from replacement of any technical means of thepresent application or combination of any two or more technical means ortechnical features provided by the present application should beincluded in the protection scope of the present application.

Front and rear in the present disclosure reference the air flowdirection of the volute structure, i.e., upstream of the air flow isfront, namely the left side of FIG. 2; while downstream of the air flowis rear, i.e., right side of FIG. 2.

The embodiment of the present application provides a volute structure,which is preferably applied to a centrifugal compressor and the like.The volute structure is configured to be a front tilting type volutestructural (as shown in FIG. 2, internal curve cavity of the volutehousing 7 faces the upstream of the air flow, i.e. left side of FIG. 2),or a rear tilting type volute structural. The volute structural ispreferably applied to double-stage centrifugal compressor or a laststage of the multi-stage centrifugal compressor in which the volutehousing is located, such that the centrifugal compressor structure ismore compact, and the stability and unit performance of the centrifugalcompressor are enhanced.

The volute structure comprises a cabinet 8, a volute housing 7, and abackflow device 5. The volute housing 7 includes an inner volute and anouter volute, which are separately provided. A fluid passage is formedbetween the inner volute and the outer volute, for fluids to passthrough. The inner volute and the backflow device 5 are arrangedtogether.

Besides, the volute housing 7 is circumferentially split into two parts:inner volute and outer volute. The inner volute and the backflow device5 are arranged together in at least the following manners: the innervolute and the backflow device 5 are fixedly connected, or the two areof an integral structure.

In the technical solution above, the volute housing is divided into twoseparate parts: an inner volute and an outer volute. Moreover, the innervolute and the backflow device are arranged together, which saves thespace occupied by the inner volute and the backflow device, downsize thestructure of fixing the volute, backflow device, and curve linkage, suchthat the volute housing and the curve may arranged close enough in thestructure. Meanwhile, it guarantees enough length of the first-stagediffuse and improves the diffusion effect of the gas entering into thefirst-stage diffuser, thereby enhancing unit performance of thecentrifugal compressor and the operation stability of the centrifugalcompressor. In addition, the technical solution above also shortens thelength of main shaft, thereby raising the threshold rotating speed ofthe rotary part of the compressor, enhancing the operation stability andcompressor performance of the centrifugal compressor.

In addition, the inner volute and the backflow device are arrangedtogether, which reduces the number of components, such that while thepneumatic part of the centrifugal compressor maintains a compactstructure, parameters of the components of the pneumatic part will becoordinated more reasonably with a better pneumatic performance. With anexample of applying the volute structure to a centrifugal compressor,the threshold rotating speed of the centrifugal compressor is related tothe main shaft length of the centrifugal compressor. By dividing thevolute housing into an outer volute and an inner volute, positions ofthe outer volute and the inner volute may be arranged more reasonablywithout changing the main shaft length of the centrifugal compressor,i.e., arrangement of the volute housing may be made without affectingthe threshold rotating speed and the unit performance of the centrifugalcompressor. In addition, by dividing the volute housing into an outervolute and an inner volute, the main shaft length may be shortened basedon the existing mechanism, with an enhanced compressor thresholdrotating speed. Enhance of the threshold rotating speed results inenhancement of the compressor stability, meanwhile the length of themain shaft is shortened, the bearing length or diameter is be shortened,the power consumption is reduced and the compressor performance isenhanced.

Furthermore, the shape of the volute will not change by dividing thevolute housing into separate inner volute and outer volute, thereby notaffecting the pneumatic performance of the volute. In addition, bydividing the volute housing into an outer volute and an inner volute,the volute casting process would be simplified. Meanwhile, an existingdigital control processing center may be employed for secondaryprocessing of the inner volute based on casting, which enhances unitperformance and cabinet universality, thereby facilitating universalitybetween different machine models, further reducing the molding times andexpenses of new boxes.

Further, the volute structure further comprises a curve passage 4provided on the backflow device 5.

In the present embodiment, the inner volute and the curve 4 aresimultaneously fixed to the backflow device 5, which saves an air supplypipeline disposed between the curve passage and the backflow device inthe existing centrifugal compressor, such that the curve passage and theinner volute would be arranged more compact in structure, therebyfurther compacting the structure of a double-stage or multi-stagecentrifugal compressor. However, a integral type volute structure isusually employed in the prior art, such that in order to mount abackflow device and avoid too small distance between the curve passageand the volute (i.e., the distance of the apex of the curve passage fromthe nearest point of volute housing along a main shaft direction), theaxial length of the main shaft has to be lengthened, which would reducethe threshold rotary speed of the compressor, thereby reducing stabilityof the compressor.

Here, the inner volute and the backflow device 5 are formed into anintegral structure through casting, i.e., the arc shape of the innervolute is formed at an external side of the backflow device 5. The innervolute is arranged on the backflow device 5. By casting, a profile ofthe inner volute would be processed by a current processing center,which expands the structure of the volute, such that the volute would bebetter matched with other pneumatic elements (impeller, diffuser) with abetter performance, without changing the volute structure at the ease ofarranging the structure, which might affect the pneumatic performance.

In order to enhance the strength of the overall structure and reduce themounting difficulty, the curve 4 and the backflow device 5 could also becasted into an integral structure.

Furthermore, the outer volute and the cabinet 8 are casted into anintegral structure, i.e., the arc shape of the outer volute is formed atan inner side of the box 8. With this structure, a improved voluteprofile may be adopted in the overall arrange, without changing thevolute structure at the ease of arranging the structure, which mightaffect the pneumatic performance.

Besides, the inner volute and the backflow device 5 are of an integralstructure, and the inner volute and the cabinet 8 are of an integralstructure, which may also be understood as such that the backflow device5 and the cabinet 8 together form a volute housing 7. In the embodiment,the outer volute is disposed on the cabinet 8, and the inner volute isdisposed on the backflow device 5. By means of precise casting andhigh-precision processing of the processing center, good connectionbetween the inner and outer volutes is guaranteed.

In the present embodiment, further, a connection part between the innervolute and the outer volute is rounded so as to avoid connectiondisplacement therebetween.

Embodiments of the present application further provide a centrifugalcompressor, comprising a volute structure according to any technicalsolution of the present application.

With reference to FIG. 2, the entire centrifugal compressor mainlycomprises a casing 1, a first-stage impellor 2, a first-stage diffuser3, a curve passage 4, a backflow device 5, a second-stage impellor 6, asecond-stage diffuser 10, a volute housing 7, and a cabinet 8.Particularly, volute front tilting means that volute tilts to the airinlet side (left side of FIG. 2). The air flow sequentially enters intothe first-stage impellor 2, the first-stage diffuser 3, curve passage 4,second-stage impellor 6, second-stage diffuser 10, and volute housing 7,finally implementing air pressure boost.

The volute structure is one of important components of pneumatic partsof the centrifugal compressor. Besides the volute structure, thecentrifugal compressor pneumatic parts further comprises an impellor anda pneumatic motor.

Further, the centrifugal compressor further comprises a casing 1. Thevolute structure further comprises a first-stage diffuser 3. The casing1, the cabinet 8, the first-stage diffuser 3 and the backflow device 5enclose a first-stage air supply cavity 9. Namely, the cabinet 8 notonly forms the volute housing 7 but also forms a first-stage air supplycavity 9.

The centrifugal compressor changes a position of setting the first-stageair supply cavity 9. The casing 1, the cabinet 8, the first-stagediffuser 3 and the backflow device 5 enclose the first-stage air supplycavity 9, such that an air supply function may be implemented withoutadding an air supply part.

As mentioned above, the centrifugal compressor is a double-stage ormulti-stage centrifugal compressor.

Embodiments of the present application further provide a refrigerantequipment, comprising a centrifugal compressor provided according to anytechnical solution of the present application. A refrigerant equipmenthaving the centrifugal compressor has a more compact centrifugalcompressor pneumatic structure with a better operation stability of thecompressor and a better pneumatic performance. The refrigerant equipmentcomprises air condition units.

In depictions of the present application, it should be understood thatorientations or positional relationships indicated by terms like“center”, “longitudinal”, “transversal”, “front”, “rear”, “left”,“right”, “vertical”, “horizontal”, “top” “bottom”, “inner”, “outer” andothers are based on the orientations or positional relationshipsillustrated in the accompanying drawings, which are only forfacilitating depiction of the present application and simplifying thedepiction, rather than indicating or suggesting that the specified meansor elements must have specific orientations or have to be constructedand operated with the specific orientations; Therefore, they should notbe understood as limitation to the protection scope of the presentapplication.

If words like “first” and “second” used here are for limitingcomponents, those skilled in the art should know that use of “first” and“second” is only for at the ease of distinguishing the spare parts;unless otherwise indicated, the words have no special meanings.

Finally, it should be stated that the embodiments above are only forillustrating the technical solution of the present application, not forlimiting it; although the present application have been described indetail with reference to the preferred embodiments, those skilled in theart should understand that the preferred embodiments of the presentapplication may be modified or part of technical features may bereplaced in equivalence; without departing from the spirit of thetechnical solution of the present application, such modifications andequivalent replacements should be covered within the scope of thetechnical solution as recited in the present application.

1. A volute structure, comprising: a cabinet, a volute housing, and abackflow device; the volute housing comprising an inner volute and anouter volute which are separately provided, a fluid passage being formedbetween the inner volute and the outer volute; and the inner volutebeing arranged with the backflow device.
 2. The volute structureaccording to claim 1, wherein the inner volute and the backflow deviceare casted integrally.
 3. The volute structure according to claim 1,wherein the outer volute and the cabinet are casted integrally.
 4. Thevolute structure according to claim 1, wherein a connection portionbetween the inner volute and the outer volute is rounded.
 5. The volutestructure according to claim 1, wherein the volute structure furthercomprises a curve passage that is fixed on the backflow device.
 6. Thevolute structure according to claim 5, wherein the curve passage and thebackflow device are casted integrally.
 7. A centrifugal compressor,comprising a volute structure having a cabinet, a volute housing, and abackflow device; the volute housing comprising an inner volute and anouter volute which are separately provided, a fluid passage being formedbetween the inner volute and the outer volute; and the inner volutebeing arranged with the backflow device.
 8. The volute structureaccording to claim 7, wherein the centrifugal compressor also comprisesa housing, and the volute structure further comprises a one-stagediffuser; and wherein the housing, the cabinet, the one-stage diffuser,and the backflow device enclose a one-stage gas supply cavity.
 9. Thevolute structure according to claim 7, wherein the centrifugalcompressor is a double-stage or multi-stage centrifugal compressor. 10.A refrigerant device, comprising a centrifugal compressor having avolute structure having a cabinet, a volute housing, and a backflowdevice; the volute housing comprising an inner volute and an outervolute which are separately provided, a fluid passage being formedbetween the inner volute and the outer volute; and the inner volutebeing arranged with the backflow device.